<template>
  <div class="channel-edit">
    <!-- 我的频道 -->
    <van-cell :border="false">
      <div slot="title" class="title-text">
        我的频道
      </div>
      <van-button type="danger" plain round size="mini" class="edit-btn" @click="isEdit = !isEdit">
        {{ isEdit ? '完成' : '编辑' }}
      </van-button>
    </van-cell>

    <van-grid class="my-grid" :gutter="10">
      <van-grid-item
        v-for="(channel, index) in myChannels"
        :key="index"
        class="grid-item"
        @click="onMyChannelClick(channel, index)"
      >
        <van-icon
          v-show="isEdit && !fixedChannels.includes(channel.id)"
          slot="icon"
          name="close"
        ></van-icon>
        <span slot="text" class="text" :class="{ active: index === active }">
          {{ channel.name }}
        </span>
      </van-grid-item>
    </van-grid>
    <!-- /我的频道 -->

    <!-- 频道推荐 -->
    <van-cell :border="false">
      <div slot="title" class="title-text">
        频道推荐
      </div>
    </van-cell>
    <van-grid class="recommend-grid" :gutter="10" direction="horizontal">
      <van-grid-item
        class="grid-item"
        icon="plus"
        v-for="(channel, index) in recommendChannels"
        :key="index"
        :text="channel.name"
        @click="onAddChannel(channel)"
      />
    </van-grid>
    <!-- /频道推荐 -->
  </div>
</template>

<script>
import { getAllChannels, addUserChannel, deleteUserChannel } from '@/api/channel'
import { mapState } from 'vuex'
import { setItem } from '@/utils/storeage'

export default {
  name: 'ChannelEdit',
  components: {},
  props: {
    myChannels: {
      type: Array,
      required: true
    },
    active: {
      type: Number,
      required: true
    }
  },
  data() {
    return {
      allChannels: [], // 所有频道
      isEdit: false, // 控制加载
      fixedChannels: [0] // 固定数组，不允许删除
    }
  },
  computed: {
    ...mapState(['user']),
    // 计算属性会观测内部依赖数据的变化
    // 如果依赖的数据发生变化，则计算属性会重新执行
    recommendChannels() {
      // 数组的filter方法:遍历数组，把符合条件的元素存储到新数组
      return this.allChannels.filter(channel => {
        // 数组的find方法:遍历数组，把符合条件的第1个元素返回
        return !this.myChannels.find(myChannel => {
          return myChannel.id === channel.id
        })
      })
    }
    /* recommendChannels() {
      const channels = []
      this.allChannels.forEach(channel => {
        const ret = this.myChannels.find(myChannel => {
          return myChannel.id === channel.id
        })

        // 如果我的频道中不包括该频道项，则收集到推荐频道
        if (!ret) {
          channels.push(channel)
        }
      })
      // 把计算结果返回
      return channels
    } */
  },
  watch: {},
  created() {
    this.loadAllChannels()
  },
  mounted() {},
  methods: {
    async loadAllChannels() {
      try {
        const { data } = await getAllChannels()
        this.allChannels = data.data.channels
      } catch (err) {
        console.log(err)
        this.$toast('数据获取失败！')
      }
    },
    async onAddChannel(channel) {
      this.myChannels.push(channel)
      // 数据持久化处理
      if (this.user) {
        try {
          // 已登录，把数据请求接口放到线上
          await addUserChannel({
            id: channel.id,
            seq: this.myChannels.length
          })
        } catch (error) {
          this.$toast('保存失败，请稍后重试')
        }
      } else {
        // 未登录，把数据存储的本地
        setItem('TOUTIAO_CHANNELS', this.myChannels)
      }
    },
    onMyChannelClick(channel, index) {
      if (this.isEdit) {
        //  1.如果是固定频道则不删除
        if (this.fixedChannels.includes(channel.id)) {
          return
        }
        // 2.编辑状态，则执行删除频道
        this.myChannels.splice(index, 1)

        // 3.如果删除的激活频道之前的频道，则更新激活的频道项
        if (index <= this.active) {
          // 让激活频道的索引-1
          this.$emit('update-active', this.active - 1, true)
        }

        // 4.处理持久化
        this.deleteChannel(channel)
      } else {
        // 非编辑状态，执行切换频道
        this.$emit('update-active', index, false)
      }
    },
    async deleteChannel(channel) {
      try {
        if (this.user) {
          // 已登录，则将数据更新到线上
          await deleteUserChannel(channel.id)
        } else {
          // 未登录，将数据更新到本地
          setItem('TOUTIAO_CHANNELS', this.myChannels)
        }
      } catch (error) {
        this.$toast('操作失败，请稍后重试')
      }
    }
  }
}
</script>

<style lang="less" scoped>
.channel-edit {
  padding-top: 85px;
  .title-text {
    font-size: 32px;
    color: #333;
  }
  .edit-btn {
    width: 104px;
    height: 48px;
    font-size: 26px;
    color: #ff7c60;
    border: #ff7c60 1px solid;
  }
  /deep/.grid-item {
    width: 160px;
    height: 86px;
    .van-grid-item__content {
      background-color: #f4f5f6;
      white-space: nowrap;
      .van-grid-item__text,
      .text {
        font-size: 28px;
        color: #222;
        margin-top: unset;
      }
      .active {
        color: red;
      }
      .van-grid-item__icon-wrapper {
        position: unset;
      }
    }
  }
  /deep/.my-grid {
    .grid-item {
      .van-icon {
        position: absolute;
        top: -10px;
        right: -10px;
        font-size: 30px;
        color: #cacaca;
        z-index: 5;
      }
    }
  }
  /deep/.recommend-grid {
    .grid-item {
      .van-icon {
        font-size: 24px;
      }
    }
  }
}
</style>
